Traditionally doors such as bifold or sliding doors have carriages or trolleys on the top or bottom which rely on being supported and guided by a tracking system whereby some doors can be called ‘top hung’ or ‘bottom hung’ doors. The tracking system comprises an aluminum extrusion system having an open track. However with top hung doors the extrusion system has to be very strong to be able to support the weight of the door hanging there-from. In some cases the top hung extrusion or a building lintel, can sag thereby causing the door to not be able to move or open.
Bottom hung doors do not suffer this sagging problem but instead the track can clog up with dirt or dust to also cause the door or window to jam or not move or open as required. A clogged up track can look unsightly and be very difficult to prevent or even clean.
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